The long term goal of the proposed research is to characterize the cognitive mechanisms i that underlie the naming process and to identify their neuroanatomical correlates, in order to provide a deeper understanding of the nature of naming disorders that result from brain damage. The specific aims are: 1) to evaluate the hypothesis that particular patterns of performance in naming tasks result from damage to distinct components of the naming process, and 2) to articulate in some detail the organization and structure of the cognitive components that are involved in the production of a word (in spoken or written form). These aims will be accomplished through a two-phase program of research. In the first phase, a large number of patients with focal brain damage will be administered a battery of tasks to identify the possible locus of damage to the cognitive/linguistic processes recruited in the naming process. Patients' performance on this battery will be used to evaluate and, where necessary, to modify the working model of the naming process, and to identify patients with relatively selective deficits to specific components of the naming process. In the second phase of the research program, patients with selective damage to a given mechanism will be tested with experimental tasks designed to test theory-driven hypotheses about the processing structure of individual components of the naming process. Detailed analyses of data generated in this phase of testing will be used to: 1) provide a more detailed hypotheses of the nature of each patient's cognitive deficit(s), 2) revise the test battery to better discriminate among disorders resulting from distinct components, and 3) evaluate hypotheses about specific] aspects of the mental representations, and the internal organizational structure, of the various components of the naming process. Finally, information about the locus of damage in patients with focal brain damage will be related to information about functional locus of damage to the naming process. The results of the proposed studies will contribute to a deeper understanding of naming disorders in brain-damaged patients - an indispensable foundation for evaluation and rehabilitation of the most common functional impairment among aphasic patients.